From 7f8d61f005228fc48e6e2ca3c9af3302cd4870af Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 3 Nov 2016 13:09:24 +0100 Subject: [PATCH] percpu: use notrace variant of preempt_disable/preempt_enable Commit 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap like events do") added a couple of this_cpu_read calls to the ftrace code. On x86 this is not a problem, since it has single instructions to read percpu data. Other architectures which use the generic variant now have additional preempt_disable and preempt_enable calls in the core ftrace code. This may lead to recursive calls and in result to a dead machine, e.g. if preemption and debugging options are enabled. To fix this use the notrace variant of preempt_disable and preempt_enable within the generic percpu code. Reported-and-bisected-by: Sebastian Ott Tested-by: Sebastian Ott Fixes: 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap like events do") Signed-off-by: Heiko Carstens Acked-by: Steven Rostedt Signed-off-by: Martin Schwidefsky --- include/asm-generic/percpu.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h index 40e887068da2..0504ef8f3aa3 100644 --- a/include/asm-generic/percpu.h +++ b/include/asm-generic/percpu.h @@ -118,9 +118,9 @@ do { \ #define this_cpu_generic_read(pcp) \ ({ \ typeof(pcp) __ret; \ - preempt_disable(); \ + preempt_disable_notrace(); \ __ret = raw_cpu_generic_read(pcp); \ - preempt_enable(); \ + preempt_enable_notrace(); \ __ret; \ }) -- 2.34.1